The present invention relates to a device for reducing noise produced by automotive vehicle components.
For example, a head cover 2 on an engine 1 is caused to vibrate as shown by two-dotted lines in FIG. 1 by vibration transmitted from a cylinder head 3, thus producing noise. So far such noise is reduced by a reinforcing rib 4 inside the head cover 2 which increases the rigidity of the latter; this is called "rib reinforcement". Alternatively, as shown in FIG. 3, elastic members 5 are interposed between the head 3 and the cover 2 to float the latter from the former, thereby preventing the transmission of vibration from the head 3 to the cover 2; this is called "floating".
Other noise sources of automotive vehicles are oil pans, timing gear cases, bodies and so on.
In the rib reinforcement as shown in FIG. 2, provision of the reinforcing rib 4 will cause increase of the overall weight of an automotive vehicle. In the floating as shown in FIG. 3, the elastic members 5 which has relatively greater thickness tends to adversely affect on the sealability.
In view of the above, a primary object of the present invention is to provide a device for reducing noise produced by automotive vehicle components, which device is referred to as a noise reduction device hereinafter for brevity and can satisfactorily reduce noise due to vibration without increasing the weight of an automotive vehicle and without adversely affecting required performances of automotive vehicle components such as sealability. The present invention, therefore, relates to a noise reduction device characterized in that a retaining plate is disposed over and spaced apart from a noise source so as not to be moved away from the noise source and that a sheet-like elastic member is compressedly interposed between the noise source and the retaining plate.
The present invention further relates to the noise reduction device of the type in which the retaining plate and sheet-like elastic member partly extend over a portion of vibration loop of the noise source.
According to the present invention, any vibration of the noise source or component of an automotive vehicle causes the sheet-like elastic member in compressed state between the noise source and the retaining plate to vibrate in unison with the noise source so that the sheet-like elastic member is distorted. The distortion will absorb the vibration energy to reduce the noise.
The noise reduction device partly extends over the portion of vibration loop of the noise source or automotive vehicle component so that satisfactory noise reduction can be attained.